In patients with cystic fibrosis (CF), chronic colonization of the lungs with Pseudomonas aeruginosa results in frequent hospitalizations and in premature mortality. P. aeruginosa can colonize surfaces in multiple ways: swarming motility, sliding motility and the formation of biofilms. Expression of components on the surface of the bacteria (e.g. type IV pili, exopolysaccharide, flagella, and rhamnolipids) is important for these activities, but current understanding of the interactions and co-regulation of these factors is incomplete. Dr. Murray has preliminary evidence that certain regulatory proteins produced by P. aeruginosa each controls multiple factors important for colonization. His research goals are to: 1) Determine the components required for surface colonization co-regulated by these proteins (using strains of P. aeruginosa that variously lack these regulatory proteins and measuring levels of pilin, flagellin, exopolysaccharide, and rhamnolipid during swarming, sliding and formation of biofilms);2) To quantitate the colonization of surfaces by these strains in a CF tissue culture model of infection (by visualizing bacterial/epithelial cell interactions with confocal microscopy and analyzing these images with COMSTAT software);and 3) To correlate in vitro surface colonization defects with abnormal chronic colonization in vivo (by measuring the recovery of bacteria, histology, and the immune response in the lungs of rats infected with these strains). Understanding these processes may lead to novel therapies. Dr. Murray will complement his experience in microbiology by learning new techniques: real time PCR, confocal microscopy, a CF tissue culture model, and a rat model of chronic pneumonia. Dr Murray's primary mentor has expertise in animal infection models and his advisory committee includes experts in microbial pathogenesis and the director of Yale's CF Center who will teach him these skills. He will take courses in translational research, immunobiology, and animal care. Through this additional training, Dr. Murray will gain the tools to become an independent investigator in the pathogenesis of chronic infection by Pseudomonas. RELEVANCE (See instructions): The bacterium Pseudomonas aeruginosa lives in the lungs of people with cystic fibrosis for many years, resulting in frequent hospitalizations. Current antibiotic therapies are not successful in eliminating the bacteria and new approaches to therapy are needed. The goal of this project is to better understand the properties of P. aeruginosa that allow it to survive in the lung so new therapies may be developed.